Flexible electromagnetic wave guide



Au .16,1949. w. D. ALLEN 2,479,288

FLEXIBLE ELECTROMAGNETIC WAVE GUIDE Filed Feb. 28, 1946 2 Shets-Sheet 1l/Vl/ENTUR WILLIAM :Dou was A LLEN 4 W 4040/? MM ATTORNEY) Aug. 16,1949. w. D. ALLEN FCLEXIBLE ELECTROMAGNETIC WAVE GUIDE 2 Sheets-Sheet 2Filed Fb. 2a, 1946 Fig. /4

Hen Y Inventor will/am A cfiiz.

2!! rue s Patented Aug. '16, 1949 FLEXIBLE.ELEGTROMAGNETICg; WAVE GUIDEI WilliamDouglas Allen, Malvern, England- V Application-February 28,1946; 'Serial,No. -650,995s- In.Great Britain March 8,1944 Se'ctionl,Public-Law 690, August-8,' 1946 1 Patent-expires March 8, 1964 I eThis:mventionirelates:toezelectroemagneticiwave guides? and:.-it.;has:for; its r maim object toi provide.

a. :wavenguide; which, ithough ;robustenough; to

stand; handling and mQuntingt-isialso; capable. of a substantial degreeof bending or out unduly; upsettingethei characteristics guider due to?a changezin sheath, 1'. eithezwall defining the guidez...

of the According; ;to;. the: .imzentionathis; obj ectz; is 'at:-: tainedby making the sheath of the-.wave. guide.

ofwwir'e meshmand surrounding. it'byp-a sleeve of flexible material.such: as. rubbers: which .conforms to: the .sheathiand towhich: the:sheath: is secured;

The rubber or: otheiriflexible; material is prefer-.-

ably moulded on to the wire-mesh sheath: or.

bondedito :it byrone of? thez prczcesses now, practisedcommerciallyifo'r securing: such materials 'to' metal. I Suchiawave-guide may; betwisted-orbent without the: crossesectionsiiofrfthesheath being: effectively altered. The secticnzlmayzgchange slightlybutithe: provisionmiLa. sleeve of flexible material of adequatethickness ensures that the change will be-graduahand thus tapered. Ifordinary wire-mesh is. emp1oyed,.in...which .the wires are at rightangles to is facilitated if the wires are arranged on the bias, e. g.45, with respect-tothelongitudinal axis of the guide; twisting is ofwires are'respectively arranged-l parallelandat right,angles-tothataxis. v a a I Sectionsof wave guide made-according-.-tothe invention :are suitable for interposing between pieces of apparatus,or lengths oi rigid waveguide, between which relative motion-is:necessary, as when high-frequency energy has to be supplied to aradiator which is mechanically oscillated.-

They may also be employed with advantage where vibration is likely tooccur, as in mobile equipment.

The invention will now be described in greater detail with reference tothe accompanying drawings which illustrate by way of example one form ofwave guide coupling made in accordance with it. In these drawings-Figure 1 is a longitudinal guide.

Figures 2 and 3 are transverse sections on the lines II-II and III-IIIrespectively of Figure 1.

Figures 4 and 5 show details of the wire mesh of which the sheath ismade.

Figures 6 to 14 show various forms of the flexible sleeve of the guide.

Referring to these hollow tubular sheath of the guide. copper wire-meshhaving from section through the twisting with-.

the crossesectionof the one. another,, bending.

facilitated if the two: sets Claims. (Cl. 178-.44.)

' thevinch'; .In. the exampleiillustrated: it is ofrectangular;crossesectiorr obyiously,-it vmaybe.

oft-other polygonallcross -sectionj or"ofrcircular or ovalCIOSSeSQOtiOll: '1 @1 Itif isr' ta be-,:1understood thatv the terms..itube and: ftubularf-Ir 'aspused in the specification hOllOwwstructures; polygonak-or circular; omovalicmssesections. .It is formedby; wrapping .gam .appropriatelyedimensioned sheetzot wince-mesh Zround;a; mandrel and soldering. theedgese The-mandrel has :the: form of ananodized Duralumin bar having a trans-;

verse section.otthesameldimensions asthe inside of: the. sheath: The;mandrel-i: has. been :omitted from the drawing for the sake of clarity;It would extend beyond the wire-mesh sheath ateachend and have its:longitudin-ai-v edges slightly. rounded. I

The-wire meshemay be;arranged with the two. sets 0t:component-.:wiresw:arranged.respectivelyparallel-;with andauriglsrtzangles; tor-the. longitudinal; axis of-.the guide,-,-a,s;shown* inFig; 4 in which the .broken-linedndicates thedirectionof the-axis. Alternatively, the wires may be arranged on-the;biasas shown*-in:Fig; e

A. short length .of; :copperstubea 2, wt rectangular cross-section; fitsoveraeaeheendpot the. sheath 1 This-tubal maybe madea-fronr'a 131606ofsheet copper bent ground; the wireemeshzsheath I on. the

'70 to 80 wires to mandrelrz- A brass washer-31s putron-each piece oitube 2 andthenaa male: ori-iemale coupling. member- 4. These. havecentral. rectangular openings fitting, the outsideiofsthewtuhee The:outer faces omends-ofi. sheath .1 ,tubel, and coupling; member-.14eareebrougntnlush and; the coupling member sweated to the tube 2, andthe tube 2 to the sheath l. Each washer 3 is sweated to the tube 2 inthe position shown.

The sheath l, and the'inner ends of the tubes 2 between the washers-3,are then surrounded by a substantial sleeve 5 of rubber. The rubber ismoulded into the space between the washers 3 and on to the sheath Iwhich is thus secured to the rubber over the whole of its area. Therubber is also caused to adhere to the inner faces of the washers 3. Ithardness, measured by a, Dunlop durometer, may be from 35 to 40. Theouter surface of the rubber sleeve is given a cylindrical form.

The invention is applicable to wave guides having a cross-section otherthan the rectangular form described with reference to the drawing.Moreover, the flexible sleeve need not be of cylindrical form nor needit be of uniform thickness as in the example illustrated. It may havelongiand'. claims: arer intended-to. includehaving either :substantiallytudinal or transverse slots or grooves so as to produce in effect athinner sleeve strengthened by longitudinal or transverse ribs. Sucharrangements are illustrated in Figs. 6, 7 and 8. In Fig. 6, the sleeve5 is provided with longitudinal ribs 5. Fig. 7 is a section of Fig. 6 onthe line VIIVII. In Fig. 8, the sleeve 5 is provided with transverseribs 1. Strips of metal may be embedded in the 1 flexible material ofthe sleeve to reinforce it. Such arrangements are illustrated inFigs. 9,.10 and 11. In Fig. 9, the sleeve 5 is re-inforced with longitudinalstrips of metal 8. Fig. 10 is a-section of Fig. 9 on the lines X--X. InFig. 11, the sleeve 5 is re-inforced with transverse strips of metal 9.

The sleeve may be of composite construction instead of in one piece. Itmay bebuilt up of two or more concentric sleeves the material of whichneed not all be of the same flexibility, as shown in Fig. 12 in whichthe sleeve is made up of two layers 5a and 5b. Inone form of compositeconstruction, as shown in Fig. 13, thewire-mesh sheath may have acoating of rubber l0 bonded to it, a layer of fabric ll over the rubbercoating, and a thick rubber sleeve I2 over the fabric.

It is not desired that the wave guide should twist, its resistance totwisting may be increased by providing a sleeve of braid l3 over theoutside of the flexible sleeve. The braid sleeve may, in a wave guidesuch as that illustrated in Fig. 1, extend between two'collars whichcover the junctions between the wire-mesh sheath and the end tubes. I

Resistance to bending may be increased by putting a rigid tube I 4 'overtheflexible sleeve 5, as shown in Fig. 14.

1. An electromagnetic wave guide comprising an innermost hollow tubeformed of conducting wire mesh, and a flexible sleeve surrounding andsecured tosaid tube, theinterior of said tube being devoid of all matterexcept air whereby the sole dielectric within the tube is an air core ofhigh power factor. r a V V 2. An electromagnetic wave guide comprisingan innermost hollow tube formed of conducting wire mesh, and a sleeve offlexible material surrounding and secured to said tube for supportingthe same and substantially maintaining the originalcross-section of thetube when the wave guide is subjected to 'flexural or torsional stress,the interior of said tube being devoid of other supporting means wherebythe sole dielectric within the tube is an air core of highpower factor.I

3. An electromagnetic wave guide comprising an'innermost hollow tubeformed of conducting wire mesh, and a rubber sleeve surroundin andbonded to said tube for supporting the same and substantiallymaintaining the original cross-section of the tube when the wave guideis subjected to, flexural or torsional stress, the interior of said tubebeing devoid of other supporting means whereby the sole dielectricwithin the tube is an air core of high power factor and of across-sectional area substantially equal to the cross-sectional areaenclosed by the tube.

4. The combination set forth in claim 2 wherein the wires ofthe mesh arearranged on the bias with respect to the longitudinal axis of the tube.

5. The combination set forth in claim 3 wherein the wires of the meshare arranged on the bias with respect to the longitudinal axis of thetube.

6. The combination set forth in claim 3 wherein the wire mesh comprisestwo sets of wires which are respectively at right angles and parallel tothe longitudinal axis of the tube.

7. The combination set forth in claim 2 wherein the flexible sleeve isprovided with ribs extending longitudinal to the axis of the wave guideand projecting outwardly from the exterior surface of the sleeve.

8. The combination set forth in claim 3 wherein the rubber sleeve isprovided with ribs extending longitudinal to the axis of the wave guideand projecting outwardly from the exterior surface of the sleeve.

9. The combination set forth in claim 2 wherein the flexible sleeve isprovided with ribs extending transverse to the axis of the wave guideand pro- 7 jecting outwardly from the exterior surface of the sleeve.

10. The combination set forth in claim 3 wherein the rubber sleeve isprovided with ribs extending transverse to the axis of the wave guideand projecting outwardly from the exterior surface of the sleeve.

WILLIAM DOUGLAS ALLEN.

REFERENCES CITED UNITED STATES PATENTS 'Date Number Name 2,193,017Bassett Mar. 12, 1940 2,287,134, Robertson June 23, 1942 2,342,736Herzog Feb. 29, 1944 2,374,493 Quayle .-Apr. 24, 1945 2,387,783 TawneyOct. 30, 1945 2,436,421

Cork Feb. 24, 1948

